如何修复 docplex 错误？它在 CPLEX 中运行良好

Question

我正在尝试创建一组关于简单 VRP 问题的约束。

我已经尝试过 add_constraint，但遇到了无效的语法错误

怎么解决这个问题？？现在我使用 add_constraint，我的错误和代码如下所示。

from docplex.mp.model import Model
md1 = Model('VRPPD')

K=[0,1,2]

D=[1,2,3,4,5,6]

D_PLUS=[0,1,2,3,4,5,6]

ccost=[2000,2000,2000]
cmax=[2,2,2]

#define decision variables 
c1 = md1.integer_var_dict([(k,i) for k in K for i in D_PLUS], name='c1')
c2 = md1.integer_var_dict([(k,i) for k in K for i in D_PLUS], name='c2')
x = md1.binary_var_dict([(k,i,j) for k in K for i in D_PLUS for j in D_PLUS], name='x')
y = md1.binary_var_dict([(k) for k in K], name='y')


#define objective functions
md1.maximize(md1.sum(y[k]*ccost[k] for k in K))

#********************************** constraint 1 entire job should be served***********************************
md1.add_constraint(md1.sum(x[k,i,j] for k in K for i in D_PLUS for j in D) == 20, 'st1')

#********************************** constraint 2 allocate vehicle***********************************
mdl.add_constraint(md1.sum(x[k,i,j] for i in D_PLUS for j in D_PLUS) <= 1000*y[k] for k in K, 'st2')

#solve and print outputs
md1.solve_details
solution = md1.solve(log_output=True)
print(solution)

Answer 1

如果你把st2改写成

for k in K:
   md1.add_constraint((md1.sum(x[k,i,j] for i in D_PLUS for j in D_PLUS) <= 1000*y[k]), 'st2'+str(k))

你的模型有效。